112 THE VOYAGE OF H.M.S. CHALLENGER. 



together, produced in front into a short sharp rostrum ; ocular lobes minute, triangular, 

 pointed ; eyes entirely absent. First free segment of the thorax with minute epimera 

 prolonged anteriorly into a spine ; remaining thoracic segments with rounded epimera, 

 extremely minute. 



Abdominal segments narrower than thoracic, first five subequal, sixth greatly 

 elongated, terminating in a short conical process. 



First pair of antennas with unequally sized nagella, the outer being the longer ; 

 rudimentary exopodite of antennas short, consisting of a single longish joint, setose at 

 its extremity. Chelae strong and stout, equally so in both sexes ; the second pair of 

 thoracic appendages much stouter than the following, modified into fossorial limbs ; 

 both these appendages without the rudimentary exopodite. Abdominal limbs well 

 developed, the exopodite divided into tm*. joints. Uropoda defective, but apparently 

 elongated and multiarticular, like those of Apseudes and the other genera of the 

 famfly. 



Remarks. — This genus, on account of its biflagellate antennules and antennas 

 furnished with an exopodite, is evidently one of the family Apseudidse, with which it 

 also agrees in the modification of the second pair of thoracic limbs. It cannot, how- 

 ever, be assigned to any of the three genera which represent that family ; from 

 Apseudes the present genus differs in having no exopodite to the first two pairs of 

 thoracic appendages ; the absence of the rudimentary exopodite in the first two 

 thoracic appendages allies Typldapseudes to Parapseudes, from which it differs 

 in that all the abdominal appendages are present, only the first four and the uropoda 

 being developed in Parapseudes. The remaining genus Sphyrapus cannot be 

 confounded with the present, differing as it does in having no rudimentary exopodite 

 to the antennules, but in having an exopodite developed upon the first pair of 

 thoracic limbs ; it agrees, however, with Typldapseudes in having the exopodite of the 

 abdominal lirnbs Inarticulate. Other differences will be apparent from a perusal of the 

 following description of Typldapseudes nereus, the only species at present known. 



Typldapseudes nereus, F. E. Beddard (PI. XV. fig. 4). 



TypMapseudes nereus, F. E. Beddard, Proc. Zool. Soc. Lond., 1880, pt. i. p. 115. 



This species is represented by a number of individuals dredged in the North 

 Atlantic, from a depth of 450 fathoms. 



The average length of the species is about 10 mm. 



The body is flattened and depressed, smooth, without any covering of hairs even on 

 the abdomen ; it is wider anteriorly and gradually narrows to the posterior extremity. 



The head and the first segment of the thorax, which are of course, fused together 



